Research On Soil Erosion And Conservation Mesures Of Expressways In Construction And Weep Model's Applicability In This Area

In this study, research on the characteristics of soil erosion on side slopes of expressways in construction is carried out along Longxian section of Baoping expressway. Situation and laws of soil erosion are analyzed on side slopes of expressways in construction by means of establishing runoff plots. And the predicted quantity of erosive soil obtained through WEPP model is compared with the real values to check WEPP model's applicability in this area. Based on the analysis above, some conclusions can be drawn as follows:(1) Both the amount and intensity of rainfall are closely related with the quantity of erosive soil in the areas we study, especially in July and August when rain is much heavier. Therefore, temporary measures should be taken to prevent the loss of soil and water before flood season.(2) The section of the Baoping expressway we study is still in construction, and all the slopes of these runoff plots are just informed disturbing ones, plants growing on them are all just planted, which mean the conditions of all these five runoff plots are closely similar with each other, in addition, the rainfall is bigger in flood season, therefore, the soil erosion of them are basically the same, only with Road cutting No.2 and Road embankment No.2 being eroded a little heavier than the other three runoff plots.(3) In this study, WEPP model is first employed in calculating and forecasting the loss of soil and water of slopes of expressways. Confined to topographic condition, the length of all the slopes we choose are not very long and the ratios of slopes are all equal with each other. The experiments show that the tendency and amount of soil erosion of all these slopes are basically the same.(4) The value of hydraulic conductivity, flow shear stress and rill soil erodibility are 14.30mm/h,1.20Pa,1.650s/m, respectively. And the comparison show a low degree of fitness in case of prediction and observation, therefore, the simulated results are not as perfect as we expected.(5) All the ME value of simulation soil erosion results is -0.61 in all these five plots according to Nash—Sutcliffe model, which reveals that the results of simulation are not as good as we expected. Therefore, WEPP model is still cannot be used to simulate and forecast the soil and water loss of expressways, and we should take more efforts to explore relevant parameters in further researches, which could guide the practice and prevent soil erosion.